A multiprocess future is a future that uses multicore evaluation if supported, otherwise it uses multisession evaluation. Regardless, its value is computed and resolved in parallel in another process.
multiprocess(expr, envir = parent.frame(), substitute = TRUE,
lazy = FALSE, seed = NULL, globals = TRUE, workers = availableCores(),
gc = FALSE, earlySignal = FALSE, label = NULL, ...)
An R expression to be evaluated.
The environment from where global
objects should be identified. Depending on the future
strategy (the evaluator
), it may also be the environment
in which the expression is evaluated.
If TRUE, argument expr
is
substitute()
:ed, otherwise not.
If FALSE
(default), the future is resolved eagerly
(immediately), otherwise not.
(optional) A L'Ecuyer-CMRG RNG seed.
(optional) a logical, a character vector,
or a named list for controlling how globals are handled.
For details, see section 'Globals used by future expressions'
in the help for future()
.
The maximum number of multiprocess futures that can be active at the same time before blocking.
If TRUE, the garbage collector run (in the process that evaluated the future) after the value of the future is collected.
Specified whether conditions should be signaled as soon as possible or not.
An optional character string label attached to the future.
Not used.
A MultiprocessFuture implemented as either a MulticoreFuture or a MultisessionFuture.
Internally multicore()
and multisession()
are used.
# NOT RUN {
## Use multiprocess futures
plan(multiprocess)
## A global variable
a <- 0
## Create multicore future (explicitly)
f <- future({
b <- 3
c <- 2
a * b * c
})
## A multiprocess future is evaluated in a separate R process.
## Changing the value of a global variable will not affect
## the result of the future.
a <- 7
print(a)
v <- value(f)
print(v)
stopifnot(v == 0)
# }
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